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5.3 General Requirements for Traps
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Fixture traps shall be self-scouring and shall have no interior partitions except where such traps are integral with the fixture or where corrosion-resistant materials of plastic or glass are used. Solid connections, slip joints, or couplings may be used on the trap inlet, trap outlet, or within the trap seal. See Figures 5.3.1-A through 5.3.1-C. Refer to Sections 4.2.15 and 7.3.7 for slip joints and their required access.

Figure 5.3.1 - A
A FIXTURE TRAP WITH SOLID CONNECTIONS
A FIXTURE TRAP WITH SOLID CONNECTIONS

Figure 5.3.1 - B
A FIXTURE TRAP WITH SLIP JOINTS
A FIXTURE TRAP WITH SLIP JOINTS

Figure 5.3.1 - C
A FIXTURE TRAP WITH THREE DIFFERENT TYPES OF JOINTS
A FIXTURE TRAP WITH THREE DIFFERENT TYPES OF JOINTS
Each fixture trap shall have a liquid seal of not less than two inches and not more than four inches.
EXCEPTIONS:
- Interceptors in Chapter 6 that provide the required trap seal.Note: Interceptors in Chapter 6 that do not provide the required trap seal shall be provided with a separate trap.
- Special conditions such as accessible fixtures, a deeper seal may be required by the Authority Having Jurisdiction in accordance with N.J.A.C. 5:23-3.3. See Figure 5.3.2

Figure 5.3.2
TRAP SEAL DEPTH
TRAP SEAL DEPTH
Traps shall be set level with respect to their water seals and, where necessary, shall be protected from freezing. See Figure 5.3.3

Figure 5.3.3
TRAPS MUST BE LEVEL AND PROTECTED FROM FREEZING
TRAPS MUST BE LEVEL AND PROTECTED FROM FREEZING
Building traps shall not be installed except where required by the Authority Having Jurisdiction in accordance with N.J.A.C. 5:23-3.3. Each building trap when installed shall be provided with a cleanout and with a relieving vent or fresh air intake on the inlet side of the trap that shall be at least one-half the diameter of the drain to which it connects. Such relieving vent or fresh air intake shall be carried above grade and terminate in a screened outlet located outside the building.
Comment: Building traps are no longer installed in modern plumbing systems. They provide a collection point for solids and other waste that may cause line stoppages. Building traps also prevent the building vent system from venting the building sewer. The Authority Having Jurisdiction may require building traps if the sewer gas in the municipal sewage system is particularly corrosive or aggressive and could damage the drain, waste, and vent piping in the building.
- The following types of traps shall be prohibited:
- Traps that depend upon moving parts to maintain their seal.
- Bell traps.
- Crown vented traps.
- Separate fixture traps that depend on interior partitions for their seal, except if made from plastic, glass or other corrosion resistant materials.
- "S" traps, of uniform internal dimension.
- Drum traps, except drum trap solids interceptors that are permitted in Section 5.3.7.
See Figure 5.3.5

Figure 5.3.5
PROHIBITED TRAPS
PROHIBITED TRAPS
- Traps that could lose their seal due to evaporation because of infrequent use shall have accessible means to replenish the trap seal or be connected to a trap primer conforming to ASSE 1018 or ASSE 1044.
- Floor drains that comply with ASME A112.6.3 shall be permitted to be fitted with a barrier type floor drain trap seal protection device complying with ASSE 1072. The device shall have an application designation marking for the type of floor and environment it has been designed and tested for (AF, AF-GW, SF, CF, CT, WF).
- Drum trap solids interceptors shall be permitted for lavatories and sinks in beauty salons, dental offices, jewelry stores, hotel and motel guest rooms, dormitories and other areas that require interception of hair, solids, and valuables.
- Solids interceptors of the drum trap type shall comply with Section 6.5.
- The depth of trap seals shall comply with Section 5.3.2.
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